The field of the disclosure relates generally to gas turbine engines and, more particularly, to a method and system for managing negative incidence in variable cycle gas turbine engine high pressure compressor stator vanes using auxiliary vanes.
At least some known variable or adaptive cycle engines are configured to operate efficiently under mixed flight conditions, such as subsonic, transonic and supersonic and which can effectively change the compressor operating line in a controlled way. During the wide range of operational conditions, high pressure compressor stator vanes may operate at negative incidence, which can result in highly three dimensional separated flows on the pressure surface of the vanes of the high pressure compressor stator. The operation of compressor vanes at negative incidence in variable cycle engines can result in conditions that could adversely affect engine performance, efficiency, and/or operability or could shorten the life expectancy of the vanes.
One condition of operating at a negative incidence or operating at a negative incidence that exceeds a certain threshold is a bluff body type separation of the flow from the surface of the high pressure compressor vane. Such separation may introduce an undesirable vibratory mode to the vane or downstream vanes. Additionally, the separation may cause a significant loss in high pressure compressor and/or engine overall performance.